LODI - Authorities have obtained a search warrant that includes a cellphone belonging to Ryan Christopher Morales, 28, the man suspected of causing a collision that killed six people Tuesday in Lodi.

Police believe Morales was driving under the influence of alcohol, and they are investigating witness claims that he was using his cellphone when the crash occurred. Lodi Police Chief Mark Helms will hold a news conference at 11 a.m. today at Hutchins Street Square to provide an update on the investigation.

Cellphone use remains a major problem on California roadways, law enforcement officials said. Distracted drivers are twice as likely to be involved in a collision, according to the National Highway Traffic Safety Administration.

"Anything that diverts a person's attention away from driving increases the potential risk of loss of life or property and is going to be a danger to society," said Officer James Smith, a spokesman for the California Highway Patrol. "For whatever reason, citizens decide they need to take that phone call or send that text message, and that's causing them to be distracted, which is ultimately causing them to be a danger to society, a danger to themselves and a danger to other citizens on the road."

The NHTSA defines distracted driving as any activity that could take a person's attention away from the task of driving. This includes cellphone use, eating, grooming, reading and adjusting the radio. In 2011, 387,000 people were injured and 3,331 killed in the United States in crashes involving a distracted driver, the NHTSA said.

"Distracted driving is a serious traffic safety concern that puts everybody on the road at risk," said Officer Joe Silva, a spokesman for the Stockton Police Department.

Lt. Sierra Brucia of the Lodi Police Department agreed.

"It's very dangerous when you're driving a vehicle to be distracted in any way," Brucia said. "Anything that distracts you while you're driving a vehicle poses a tremendous risk to the public."

In 2008, California enacted a law prohibiting drivers from using hand-held wireless devices while operating motor vehicles. Since then, authorities have stiffened fines and penalties and stressed the dangers of distracted driving, but studies show that cellphone use among motorists is still on the rise.

A 2012 study conducted on behalf of the California Office of Traffic Safety and the Safe Transportation Research and Education Center at University of California Berkeley revealed a disturbing trend. Despite law enforcement efforts, distracted-driving rates in California increased from 4.2 percent in 2011 to 6.4 percent in 2012, the study said. San Joaquin County had the state's second-highest rate of distracted driving at 10.9 percent.

Distracted drivers can face fines and penalty assessments totaling nearly $200 for a first offense and more than $300 for a subsequent offense. Those who cause collisions can face criminal prosecution, Smith said.

"You can be charged," he said. "In the event that somebody's on a cellphone, if they are involved in a collision that they are at fault for and they cause the death of another individual, they can potentially be charged with felony vehicular manslaughter with gross negligence."